Dunnage conversion machines, also referred to as converters, generally convert a sheet stock material into a strip of dunnage. The dunnage is then placed in a container with one or more objects for shipment.
Some converters produce a dunnage product primarily to provide cushioning in a packaging container to prevent or minimize damage to the contents during shipment. U.S. Pat. No. 5,674,172, for example, which is hereby incorporated herein by reference, discloses a cushioning conversion machine for converting a sheet stock material into a cushioning dunnage product. The cushioning conversion machine includes a forming assembly that causes inward rolling of the lateral edges of the sheet stock material to form a strip having a three-dimensional shape with lateral pillow-like portions separated by a thin central band. The forming assembly includes a shaping member over which the sheet stock material is drawn and a converging chute cooperative with the shaping member to roll the edges of the stock material inward to form the lateral pillow-like portions. A feed mechanism downstream of the forming assembly pulls the stock material through the forming assembly. The feed mechanism also connects overlapping layers of stock material along the thin central band. The feed mechanism has a pair of rotating gear-like members that engage and pull the stock material over the shaping member, through the converging chute, and connect, by coining, the overlapping layers in the thin central band to maintain the three-dimensional shape of the strip. The conversion machine further includes a cutting mechanism for cutting the strip into cut sections, or pads, of a desired length for use as a protective cushioning dunnage product.
Other converters produce a dunnage product primarily to fill voids in a packaging container to prevent or minimize shifting of the contents during shipment. These machines typically operate at relatively high speeds. An exemplary dunnage converter is disclosed in International Patent Application No. PCT/US2001/018678, published under Publication No. WO 01/0194107 on Dec. 13, 2001, and International Patent Application No. PCT/US2003/012301, filed on Apr. 22, 2003, and published under Publication No. WO 03/089163 on Oct. 30, 2003, both of which are hereby incorporated herein by reference.
An exemplary machine of this type includes a forming assembly for shaping a sheet stock material into a continuous strip of dunnage and a pulling assembly for advancing the sheet material through the forming assembly. The forming assembly includes a funnel portion, similar to a converging chute, through which the sheet stock material passes for shaping the sheet stock material into the strip of dunnage and directing the formed strip to the pulling assembly. The pulling assembly includes at least two opposed grippers, at least one of which is moveable through a dunnage transfer region in opposition to the other gripper. The grippers are cooperative to define an aperture therebetween and to grip the sheet stock material therein and advance it through the transfer region. The moving gripper includes a plurality of paddles that aid in defining the aperture and in engaging the sheet stock material. The grippers can help to crease the crumpled folds in the strip to help it maintain its shape. Due to the aperture between the grippers, however, the grippers generally cannot coin or stitch together the layers of stock material passing therebetween, in contrast to the gear-like members in the aforementioned cushioning conversion machine.